Charged particle beam writing apparatus, method of adjusting beam incident angle to target object surface, and charged particle beam writing method

ABSTRACT

A charged particle beam writing apparatus according to one aspect of the present invention includes an emission unit to emit a charged particle beam, an electron lens to converge the charged particle beam, a blanking deflector, arranged backward of the electron lens with respect to a direction of an optical axis, to deflect the charged particle beam in the case of performing a blanking control of switching between beam-on and beam-off, a blanking aperture member, arranged backward of the blanking deflector with respect to the direction of the optical axis, to block the charged particle beam having been deflected to be in a beam-off state, and a magnet coil, arranged in a center height position of the blanking deflector, to deflect the charged particle beam.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.15/719,820, filed Sep. 29, 2017, which is a divisional of U.S.application Ser. No. 14/943,243, filed on Nov. 17, 2015, which is adivisional of U.S. application Ser. No. 14/155,604, filed on Jan. 15,2014, which claims priority under 35 U.S.C. 119 to Japanese ApplicationNo. 2013-007682 filed on Jan. 18, 2013; the entire contents of each ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a charged particle beam writingapparatus, a method of adjusting a beam incident angle to a targetobject surface, and a charged particle beam writing method. Morespecifically, for example, the present invention relates to a method ofadjusting an incident angle of an electron beam to the target objectsurface in an electron beam writing apparatus that irradiates electronbeams onto the target object while performing a blanking operation.

Description of Related Art

The lithography technique that advances miniaturization of semiconductordevices is extremely important as being a unique process wherebypatterns are formed in semiconductor manufacturing. In recent years,with high integration of LSI, the line width (critical dimension)required for semiconductor device circuits is decreasing year by year.For forming a desired circuit pattern on such semiconductor devices, amaster or “original” pattern (also called a mask or a reticle) of highaccuracy is needed. Thus, the electron beam (EB) writing technique,which intrinsically has excellent resolution, is used for producing sucha high-precision master pattern.

FIG. 19 is a conceptual diagram for explaining operations of a variableshaped electron beam writing or “drawing” apparatus. As shown in thefigure, the variable shaped electron beam writing apparatus operates asdescribed below. A first aperture 410 has a quadrangular opening 411 forshaping an electron beam 330. A second aperture 420 has a variable-shapeopening 421 for shaping the electron beam 330 having passed through theopening 411 of the first aperture 410 into a desired quadrangular shape.The electron beam 330 emitted from a charged particle source 430 andhaving passed through the opening 411 is deflected by a deflector topass through a part of the variable-shape opening 421 of the secondaperture 420, and thereby to irradiate a target object or “sample” 340placed on a stage which continuously moves in one predetermineddirection (e.g., the x direction) during the writing. In other words, aquadrangular shape that can pass through both the opening 411 and thevariable-shape opening 421 is used for pattern writing in a writingregion of the target object 340 on the stage continuously moving in thex direction. This method of forming a given shape by letting beams passthrough both the opening 411 of the first aperture 410 and thevariable-shape opening 421 of the second aperture 420 is referred to asa variable shaped beam (VSB) system.

For example, in a writing apparatus of the VSB system, one shot beam isformed by a blanking operation. Generally, the writing apparatus has adeflection function for deflecting a plurality of beams, at a subsequentstage of a blanking deflector, and emits a beam to the surface of atarget object while deflecting the beam by the beam deflection function(refer to, e.g., Japanese Patent Application Laid-open (JP-A) No.2000-251827).

Then, in order to increase the position accuracy of writing, it isnecessary that the beam incident angle to the target object surface doesnot change even when a blanking voltage changes during a beam-on period.For example, in the case of not performing a beam deflection other thana blanking operation, it is desirable that a beam incident angle to thetarget object surface is always perpendicular even when a blankingvoltage changes during a beam-on period. If the incident angle deviatesfrom a perpendicular incidence, a positional deviation will occur at thebeam irradiation position on the target object surface when defocusingoccurs. To solve this problem, it is necessary to measure an incidentangle (a landing angle) of a beam in the case of performing deflectionof the beam by fine-tuning a blanking voltage of during a beam-onperiod. However, with respect to voltage used for a blanking operation,generally, binary values of voltage of during a beam-on period and abeam-off period are set in the amplifier that applies a voltage to ablanking deflector in order to secure a blanking speed (response) andvoltage stability. For example, a voltage used for a blanking operationis configured by binary values, such as 0V and several V. Since a beamdeflected by the voltage of during a beam-off period is blocked by theblanking aperture, it does not reach the target object surface.Therefore, the blanking voltage of during a beam-on period cannot befine-tuned, and therefore it is difficult to measure a beam incidentangle by using the voltage of an existing blanking operation.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a chargedparticle beam writing apparatus includes an emission unit configured toemit a charged particle beam, an electron lens configured to convergethe charged particle beam, a blanking deflector, arranged backward ofthe electron lens with respect to a direction of an optical axis,configured to deflect the charged particle beam in a case of performinga blanking control of switching between beam-on and beam-off, a blankingaperture member, arranged backward of the blanking deflector withrespect to the direction of the optical axis, configured to block thecharged particle beam having been deflected to be in a beam-off state,and a magnet coil, arranged in a center height position of the blankingdeflector, configured to deflect the charged particle beam.

In accordance with another aspect of the present invention, a chargedparticle beam writing apparatus includes an emission unit configured toemit a charged particle beam, an electron lens configured to convergethe charged particle beam, a blanking deflector, arranged backward ofthe electron lens with respect to a direction of an optical axis,configured to deflect the charged particle beam in a case of performinga blanking control of switching between beam-on and beam-off, a blankingaperture member, arranged backward of the blanking deflector withrespect to the direction of the optical axis, configured to block thecharged particle beam having been deflected to be in a beam-off state,and a plurality of magnet coils, arranged backward of the blankingdeflector with respect to the direction of the optical axis, configuredto deflect the charged particle beam, wherein a magnetic field formed bythe plurality of magnet coils is adjusted so that an intersection of theoptical axis and an extended line of a trajectory of the chargedparticle beam deflected by the plurality of magnet coils is located in acenter height position of the blanking deflector.

Further, in accordance with another aspect of the present invention, amethod of adjusting a beam incident angle to a target object surfaceincludes applying, using a blanking deflector arranged backward of anelectron lens with respect to a direction of an optical axis, a voltagefor beam-on to the blanking deflector, converging, using the electronlens and a magnet coil arranged in a center height position of theblanking deflector, a charged particle beam by varying a voltage to beapplied to the electron lens while supplying, to the magnet coil, acurrent for a deflection amount smaller than a deflection amount forperforming deflection to make a beam-off state by the blankingdeflector, and measuring a positional deviation amount of an irradiationposition of the charged particle beam irradiating a target object, foreach voltage to be applied to the electron lens; determining whether thepositional deviation amount is within an allowable value, for the eachvoltage to be applied to the electron lens; and adjusting the eachvoltage to be applied to the electron lens so that the positionaldeviation amount is within the allowable value.

Moreover, in accordance with another aspect of the present invention, amethod of adjusting a beam incident angle to a target object surfaceincludes applying, using a blanking deflector arranged backward of anelectron lens with respect to a direction of an optical axis, a voltagefor beam-on to the blanking deflector, converging, using the electronlens and a plurality of magnet coils arranged backward of the blankingdeflector with respect to the direction of the optical axis, a chargedparticle beam by varying a voltage to be applied to the electron lenswhile supplying, to the plurality of magnet coils, a current for adeflection amount which is smaller than a deflection amount forperforming deflection to make a beam-off state by the blankingdeflector, where an intersection of the optical axis and an extendedline of a trajectory of the charged particle beam deflected by theplurality of magnet coils is located in a center height position of theblanking deflector, and measuring a positional deviation amount of anirradiation position of the charged particle beam irradiating a targetobject, for each voltage to be applied to the electron lens; determiningwhether the positional deviation amount is within an allowable value,for the each voltage to be applied to the electron lens; and adjustingthe each voltage to be applied to the electron lens so that thepositional deviation amount is within the allowable value.

Moreover, in accordance with another aspect of the present invention, acharged particle beam writing method includes writing a pattern on atarget object while performing a blanking operation by the blankingdeflector, using a charged particle beam whose incident angle to asurface of the target object has been adjusted by one of theabove-described method of adjusting a beam incident angle to the surfaceof the target object.

Furthermore, in accordance with another aspect of the present invention,a charged particle beam writing apparatus includes an emission unitconfigured to emit a charged particle beam, an electron lens configuredto converge the charged particle beam, a blanking deflector, arrangedbackward of the electron lens with respect to a direction of an opticalaxis, configured to deflect the charged particle beam in a case ofperforming a blanking control of switching between beam-on and beam-off,a blanking aperture member, arranged backward of the blanking deflectorwith respect to the direction of the optical axis, configured to blockthe charged particle beam having been deflected to be in a beam-offstate, a first amplifier configured to apply a voltage for beam-on and avoltage for beam-off to the blanking deflector, and a second amplifier,connected in parallel with the first amplifier to the blankingdeflector, configured to apply, to the blanking deflector, a voltage fordeflecting the charged particle beam to be in an extent of deflectionnot to trigger a beam-off state from a beam-on state by the blankingdeflector.

Furthermore, in accordance with another aspect of the present invention,a method of adjusting a beam incident angle to a target object surfaceincludes setting a voltage to be applied to an electron lens forconverging a charged particle beam; controlling the charged particlebeam to be in a beam-on state by a blanking deflector arranged backwardof the electron lens with respect to a direction of an optical axis;measuring an irradiation position of the charged particle beamirradiating a mark arranged at a height position different from a firstfocus position and a second focus position, in the beam-on state, foreach of the first focus position and each of the second focus positionadjusted by an objective lens arranged at a subsequent stage of theblanking deflector, and moving a center of the charged particle beam toa side of a center of the objective lens so that a measured positionaldeviation amount between the irradiation positions becomes less than orequal to a first threshold value, by using a magnet coil arrangedbetween the blanking deflector and the objective lens; deflecting thecharged particle beam to be in an extent of deflection not to trigger abeam-off state from the beam-on state by the blanking deflector,treating a center height position of the blanking deflector as adeflection fulcrum; measuring, in a state of the charged particle beamhaving been deflected, the irradiation position of the charged particlebeam irradiating the mark, for the each of the first focus position andthe each of the second focus position adjusted by the objective lens,and moving the center of the charged particle beam to the side of thecenter of the objective lens by using the magnet coil so that a measuredpositional deviation amount between the irradiation positions becomesless than or equal to the first threshold value; determining whether adifference between a movement amount of the center of the chargedparticle beam in the beam-on state and a movement amount of the centerof the charged particle beam in a deflected state is less than or equalto a second threshold value; and repeating each step while varying thevoltage to be applied to the electron lens until the difference becomessmaller than the second threshold value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram showing a configuration of a writingapparatus according to the first embodiment;

FIG. 2 is a conceptual diagram for explaining each region according tothe first embodiment;

FIGS. 3A and 3B are conceptual diagrams showing comparison of the casesof blanking voltage change and no blanking voltage change when acrossover position is set to the center height position of the blankingdeflector according to the first embodiment;

FIGS. 4A and 4B are conceptual diagrams showing comparison of the casesof blanking voltage change and no blanking voltage change when acrossover position deviates from the center height position of theblanking deflector according to the first embodiment;

FIGS. 5A to 5D show a relation between the deflection fulcrum positionand the crossover position at the time of the blanking operationaccording to the first embodiment;

FIGS. 6A and 6B show a relation between a beam incident angle and afocus position according to the first embodiment;

FIG. 7 is a conceptual diagram showing a configuration of a magnet coilaccording to the first embodiment;

FIG. 8 is a flowchart showing main steps of a beam incident angleadjustment method according to the first embodiment;

FIGS. 9A and 9B are conceptual diagrams for explaining a beam deflectionby a magnet coil according to the first embodiment;

FIG. 10 shows an example of a blanking trajectory and a beam trajectoryby a coil according to the first embodiment;

FIG. 11 is a conceptual diagram for explaining an arrangement positionof a magnet coil according to the first embodiment;

FIG. 12 is a conceptual diagram showing a configuration of a writingapparatus according to the second embodiment;

FIG. 13 is a conceptual diagram for explaining an arrangement positionof a plurality of magnet coils and a beam deflection by a plurality ofmagnet coils according to the second embodiment;

FIG. 14 is a conceptual diagram showing a configuration of a writingapparatus according to the third embodiment;

FIG. 15 is a conceptual diagram showing a configuration of a writingapparatus according to the fourth embodiment;

FIG. 16 is a conceptual diagram showing another configuration of awriting apparatus according to the fourth embodiment;

FIG. 17 is a flowchart showing main steps of a beam incident angleadjustment method according to the fourth embodiment;

FIG. 18 shows an example of the focus position according to the fourthembodiment; and

FIG. 19 is a conceptual diagram for explaining an operation of avariable-shaped electron beam writing apparatus.

DETAILED DESCRIPTION OF THE INVENTION

In the following embodiments, there will be described a configuration inwhich an electron beam is used as an example of a charged particle beam.However, the charged particle beam is not limited to the electron beam,and other charged particle beam such as an ion beam may also be used.Moreover, a variable shaped beam type writing apparatus will bedescribed as an example of a charged particle beam apparatus.

In the following embodiments, there will be described an apparatus andmethod that enables a beam incident angle to the target object surfacenot to change even when a blanking voltage changes during a beam-onperiod.

First Embodiment

FIG. 1 is a conceptual diagram showing the configuration of a writingapparatus according to the first embodiment. In FIG. 1, a writing (or“drawing”) apparatus 100 includes a writing unit 150 and a control unit160. The writing apparatus 100 is an example of a charged particle beamwriting apparatus, and, particularly, it is an example of a variableshaped beam (VSB) type writing apparatus. The writing unit 150 includesan electron lens barrel 102 and a writing chamber 103. In the electronlens barrel 102, there are arranged an electron gun assembly 201, anelectron lens 211, an illumination lens 202, a blanking deflector 212, amagnet coil 216, a blanking aperture 214, a first aperture 203, aprojection lens 204, a deflector 205, a second aperture 206, anobjective lens 207, a main deflector 208, a sub deflector 209 and adetection device 220. In the writing chamber 103, there is arranged anXY stage 105, on which a target object or “sample” 101 such as a maskserving as a writing target is placed when performing writing. Thetarget object 101 is, for example, an exposure mask used formanufacturing semiconductor devices. The target object 101 may be, forexample, a mask blank on which resist is applied and a pattern has notyet been formed. A mark 106 is formed at a position, different from theposition where the target object 101 is arranged, on the surface of theXY stage 105. It is preferable for the mark 106 to have the shape of across, for example. It is preferable for the magnet coil 216 to beplaced in the center height position of the blanking deflector 212. Apair of electrodes, for example, is used as the blanking deflector 212.

The control unit 160 includes a control computer 110, a memory 111, anexternal interface (I/F) circuit 112, a control circuit 120, a DAC(digital analog converter) amplifier 122, a lens control circuit 130, acoil control circuit 132, and an amplifier 138. The control computer110, the memory 111, the external interface (I/F) circuit 112, thecontrol circuit 120, the lens control circuit 130, the coil controlcircuit 132, and the amplifier 138 are mutually connected through a bus(not shown).

In the control computer 110, there are arranged a measurement unit 60, apositional deviation amount calculation unit 62, a determination unit64, and a writing control unit 66. Each function, such as themeasurement unit 60, the positional deviation amount calculation unit62, the determination unit 64, and the writing control unit 66 may beconfigured by hardware such as an electronic circuit or by software suchas a program causing a computer to implement these functions.Alternatively, it may be configured by a combination of hardware andsoftware. Data which is input and output to/from the measurement unit60, the positional deviation amount calculation unit 62, thedetermination unit 64, and the writing control unit 66 and data beingcalculated are stored in the memory 112 each time.

FIG. 1 shows a configuration necessary for explaining the firstembodiment. Other configuration elements generally necessary for thewriting apparatus 100 may also be included. For example, a multi-stagedeflector of two stages of the main deflector 208 and the sub deflector209 is used for position deflection in this case, but a single stagedeflector or a multiple stage deflector of three or more stages may alsobe used. Input devices, such as a mouse and a keyboard, and a monitoringdevice, etc. may also be connected to the writing apparatus 100.Moreover, although the blanking aperture 214 is arranged upper than thefirst aperture 203 in the example of FIG. 1, it is not limited thereto.Any position is acceptable as long as a blanking operation can beperformed. For example, it may be arranged lower than the first aperture203 or the second aperture 206.

FIG. 2 is a conceptual diagram for explaining each region according toEmbodiment 1. In FIG. 2, a writing region 10 of the target object 101 isvirtually divided into a plurality of strip-like stripe regions 20 eachhaving a width deflectable by the main deflector 208 in the y direction.Then, each stripe region 20 is divided into a plurality of subfields(SFs) 30 (small regions) each having the size deflectable by the subdeflector 209. Shot figures 52, 54, and 56 are written at correspondingshot positions of each SF 30.

A digital signal for blanking control is output from the control circuit120 to the DAC amplifier 122 to perform blanking control. Then, in theDAC amplifier 122 for blanking control, the digital signal is convertedto an analog signal, and amplified to be applied as a deflection voltageto the blanking deflector 212. An electron beam 200 is deflected by thisdeflection voltage in order to control an irradiation time (dose) ofeach shot.

A digital signal for main deflection control is output from the controlcircuit 120 to a DAC amplifier (not shown). Then, in the DAC amplifierfor main deflection control, the digital signal is converted to ananalog signal, and amplified to be applied as a deflection voltage tothe main deflector 208. The electron beam 200 is deflected by thisdeflection voltage, and thereby each shot beam is deflected to areference position in a target SF 30 among virtually divided mesh likesubfields (SFs) 30.

A digital signal for sub deflection control is output from the controlcircuit 120 to a DAC amplifier (not shown). Then, in the DAC amplifierfor sub deflection control, the digital signal is converted to an analogsignal, and amplified to be applied as a deflection voltage to the subdeflector 209. The electron beam 200 is deflected by this deflectionvoltage, and thereby each shot beam is deflected to each shot positionin the target SF 30.

The writing apparatus 100 performs writing processing in each striperegion 20 by using a multiple stage deflector. In this case, a two-stagedeflector composed of the main deflector 208 and the sub deflector 209is used as an example. While the XY stage 105 is continuously moving inthe −x direction, for example, the first stripe region 20 is written inthe x direction. After the first stripe region 20 has been written, thesecond stripe region 20 is written similarly or in the oppositedirection. Then, in the same way, the third and subsequent striperegions 20 are written. The main deflector 208 deflects the electronbeam 200 in sequence to a reference position of the SF 30 so as tofollow the movement of the XY stage 105. The sub deflector 209 deflectsthe electron beam 200 from the reference position of each SF 30 to eachshot position of an irradiating beam in the SF30 concerned. Thus, thesizes of the deflection regions of the main deflector 208 and the subdeflector 209 are different from each other. The SF 30 is the smallestdeflection region in the deflection regions of the multiple stagedeflector.

The electron beam 200 emitted from the electron gun assembly 201 (anemission unit) is converged by the electron lens 211 at a predeterminedheight position in the blanking deflector 212, for example, and aconvergence point (crossover: C.O.) is formed. When passing through theblanking deflector 212 which is arranged backward of the electron lens211 with respect to the direction of the optical axis, beam-on orbeam-off is controlled by the blanking deflector 212 controlled by adeflection signal from the DAC amplifier 122 for blanking. In otherwords, in the case of blanking control of switching between beam-on andbeam-off, the blanking deflector 212 deflects the electron beam. Theelectron beam having been deflected in order to be in a beam-off stateis blocked by the blanking aperture 214 (a blanking aperture member)arranged backward of the blanking deflector 212 with respect to thedirection of the optical axis. That is, in the beam-on state, it iscontrolled to pass through the blanking aperture 214, and in thebeam-off state, it is deflected so that the entire beam may be blockedby the blanking aperture 214. The electron beam 200 that has passedthrough the blanking aperture 214 during the period from a beam-offstate to a beam-on state and again changing to a beam-off state servesas one shot of the electron beam. The blanking deflector 212 controlsthe direction of the passing electron beam 200 to alternately generate abeam-on state and a beam-off state. For example, it is acceptable toapply to the blanking deflector 212 a voltage of 0V (or not to apply anyvoltage) when in a beam-on state, and a voltage of several V when in abeam-off state. The dose per shot of the electron beam 200 to irradiatethe target object 101 is adjusted depending upon an irradiation time “t”of each shot.

As described above, each shot of the electron beam 200, which isgenerated by passing through the blanking deflector 212 and the blankingaperture 214, irradiates the whole of the first shaping aperture 203,having a quadrangular opening, by the illumination lens 202. Here, theelectron beam 200 is first shaped to a quadrangle. Then, after havingpassed through the first shaping aperture 203, the electron beam 200 ofthe first aperture image is projected onto the second shaping aperture206 by the projection lens 204. The first aperture image on the secondshaping aperture 206 is deflected and controlled by the deflector 205 soas to change (variably shape) the shape and size of the beam. Suchvariable beam shaping is performed for each shot, and, usually, eachshot is shaped to have a different shape and size. Then, after havingpassed through the second shaping aperture 206, the electron beam 200 ofthe second aperture image is focused by the objective lens 207, anddeflected by the main deflector 208 and the sub deflector 209 to reach adesired position on the target object 101 placed on the XY stage 105which moves continuously. FIG. 1 shows the case of using multiple stagedeflection of the main and sub deflection for position deflection. Insuch a case, the main deflector 208 may deflect the electron beam 200 ofa shot concerned to a reference position in an SF 30 while following themovement of the stage, and the sub deflector 209 may deflect the shotbeam to each irradiation position in the SF. A figure pattern defined inwriting data is written by repeating such operations and combining ashot figure of each shot.

In the case of the DAC amplifier 122 for blanking control beingunstable, a voltage may change during a beam-on period. For example,there occurs a voltage change of several mV (e.g., ±5 mV), or a largervoltage change may occur. The electron beam 200 passing through theblanking deflector 212 is deflected by such change.

FIGS. 3A and 3B are conceptual diagrams showing comparison of a blankingvoltage change and no blanking voltage change when a crossover positionis set to the center height position of the blanking deflector accordingto the first embodiment. FIG. 3A shows the case where a blanking voltage(e.g., 0V) at the beam-on time is applied to the blanking deflector 212and no voltage change (or a change of an ignorable extent) occurs in theblanking voltage. Moreover, FIG. 3A shows the case where no beamdeflection other than a blanking operation is performed by the deflector205 for shaping, the sub deflector 209, and the main deflector 208, andthe beam passes along the optical axis, for example. In FIG. 3A, theelectron beam 200 emitted from the electron gun assembly 201 (emissionunit) is controlled by the electron lens 211 to form a convergence point(crossover: C.O.) in the center height position H in the blankingdeflector 212. Since it is in the beam-on state in this case, theelectron beam 200 passes without being blocked by the blanking deflector212. An optical path of the crossover system is shown in FIG. 3A. Theelectron beam which has passed through the blanking deflector 212illuminates the whole of the first shaping aperture 203 by theillumination lens 202. Then, the electron beam 200 of the first apertureimage which has passed through the first shaping aperture 203 isprojected to the opening formed in the second shaping aperture 206 bythe projection lens 204. The electron beam 200 of the second apertureimage which has passed through the second shaping aperture 206 isfocused to form an image on the surface of the target object 101 by theobjective lens 207. In this configuration, the electron beam 200perpendicularly enters the surface of the target object 101. In otherwords, the beam incident angle θ is 0°.

FIG. 3B shows the state, changed from the state of FIG. 3A, where avoltage change in the extent not to trigger a beam-off state occurs inthe blanking voltage to be applied to the blanking deflector 212. Asshown in FIG. 3B, the beam is deflected in the center height position Hof the blanking deflector 212 by a change of the blanking voltage.However, when the crossover position is set to the center heightposition of the blanking deflector 212, even if a blanking voltagechange occurs, the electron beam 200 enters the surface of the targetobject 101 at an angle substantially equivalent to a perpendicularincidence. In other words, it is possible to make the beam incidentangle θ be approximately 0°. In this configuration, since the crossoverposition does not deviate from the optical axis, the electron beam 200can perpendicularly enter the surface of the target object 101.

FIGS. 4A and 4B are conceptual diagrams showing comparison of a blankingvoltage change and no blanking voltage change when a crossover positiondeviates from the center height position of the blanking deflectoraccording to the first embodiment. FIG. 4A shows the case where ablanking voltage (e.g., 0V) at the beam-on time is applied to theblanking deflector 212 and no voltage change (or a change of anignorable extent) occurs in the blanking voltage. Moreover, FIG. 4Ashows the case where no beam deflection other than a blanking operationis performed by the deflector 205 for shaping, the sub deflector 209,and the main deflector 208, and the beam passes along the optical axis,for example. In FIG. 4A, the electron beam 200 emitted from the electrongun assembly 201 (emission unit) is adjusted by the electron lens 211 toform a convergence point (crossover: C.O.) at a position higher than thecenter height position H in the blanking deflector 212, for example.Since it is in the beam-on state in this case, the electron beam 200passes without being blocked by the blanking deflector 212. An opticalpath of the crossover system is shown in FIG. 4A. The electron beamwhich has passed through the blanking deflector 212 illuminates thewhole of the first shaping aperture 203 by the illumination lens 202.Then, the electron beam 200 of the first aperture image which has passedthrough the first shaping aperture 203 is projected to the openingformed in the second shaping aperture 206 by the projection lens 204.The electron beam 200 of the second aperture image which has passedthrough the second shaping aperture 206 is focused to form an image onthe surface of the target object 101 by the objective lens 207. In thisconfiguration, the electron beam 200 perpendicularly enters the surfaceof the target object 101 so that the crossover position may not deviatefrom the optical axis as described later. In other words, the beamincident angle θ is 0°.

FIG. 4B shows the state, changed from the state of FIG. 4A, where avoltage change in the extent not to trigger a beam-off state occurs inthe blanking voltage to be applied to the blanking deflector 212. Asshown in FIG. 4B, the beam is deflected in the center height position Hof the blanking deflector 212 by a change of the blanking voltage.However, when the crossover position is set to be higher than the centerheight position of the blanking deflector 212, if a blanking voltagechange occurs, the electron beam 200 enters the surface of the targetobject 101 from the direction displaced from the vertical direction. Inother words, the beam incident angle θ is not 0°. Consequently, in thedefocused state, the beam irradiation position on the target object 101deviates from a designed desired position. It means that, in FIG. 4B,from the point of view of the beam after deflection, the crossoverposition has apparently moved to the position of the broken line in theblanking deflector 212 from the position on the optical axis asdescribed later.

FIGS. 5A to 5D show a relation between the deflection fulcrum positionand the crossover position at the time of the blanking operationaccording to the first embodiment. In FIG. 5A, it is adjusted to form aconvergence point (crossover: C.O.), by the electron lens 211, in thecenter height position H in the blanking deflector 212. When a voltageis applied to the blanking deflector 212 and the electron beam 200 isdeflected, the deflection fulcrum is located in the center heightposition H of the blanking deflector 212. When the crossover position islocated in the center height position H of the blanking deflector 212,since the deflection fulcrum and the position are in accordance, thecrossover position is on the optical axis. Therefore, as shown in FIG.5C, the final crossover position is also formed at a position on theoptical axis. On the other hand, as shown in FIG. 4B, when the crossoverposition deviates from the center height position H of the blankingdeflector 212, the crossover position and the deflection fulcrumposition do not accord with each other as shown in FIG. 5B. As describedabove, since the deflection fulcrum is located in the center heightposition H of the blanking deflector 212, from the point of view of thebeam after deflection, the crossover position is apparently on theextended line of both the beam trajectory after deflection and thedeflection fulcrum. Therefore, it means that the crossover position hasmoved to the position of the point B from the position of the point A onthe optical axis. In other words, the crossover position is formed atthe position displaced from the optical axis. As shown in FIG. 5D, thefinal crossover position of the beam is located at the positiondisplaced from the optical axis by ΔL. Therefore, the beam deflected bythe change of the blanking voltage enters the target object 101 at thebeam incident angle θ which is not a perpendicular incidence of θ being0. Consequently, when the focus position is displaced (when defocused),the center position of the irradiating beam deviates from a designeddesired position. On the other hand, as shown in FIG. 4A, in the statewhere there is no change of blanking voltage, since the deflectionfulcrum is not formed at all in the blanking deflector 212, thecrossover position is on the optical axis. Therefore, in such a case,the beam enters the target object 101 at a perpendicular incidence of θbeing 0 (θ=0). In the example described above, the crossover positiondeviates higher from the center height position H in the blankingdeflector 212. However, even when it deviates downward, the result thatthe final crossover position of the beam is displaced from the opticalaxis can also be obtained.

FIGS. 6A and 6B show a relation between a beam incident angle and afocus position according to the first embodiment. As shown in FIG. 6A,when a focus position is focused on the surface of the target object101, even if the beam incident angle θ is not 0° (even if the beam isnot incident perpendicularly), the irradiation position of the beam is adesigned desired position. On the other hand, as shown in FIG. 6B, whena focus position deviates (defocused) from the surface of the targetobject 101, if the beam incident angle θ is not 0° (if the beam is notincident perpendicularly), the irradiation position of the beam deviatesfrom a designed desired position by a positional deviation amount Δx.

Then, according to the first embodiment, the electron lens 211 isadjusted so that a crossover position may be located in the centerheight position of the blanking deflector 212 in order to adjust a beamincident angle. It is necessary for such an adjustment to deflect a beamso that a deflection fulcrum may be formed in the center height positionH of the blanking deflector 212 by using a deflection amount in theextent not to trigger a beam-off state during the beam-on period. Thus,according to the first embodiment, the magnet coil 216 is arranged inthe center height position of the blanking deflector 212, and theelectron beam 200 is deflected by a deflection amount in the extent notto trigger a beam-off state.

FIG. 7 is a conceptual diagram showing the configuration of a magnetcoil according to the first embodiment. In FIG. 7, the magnet coil 216(e.g., an alignment coil) is formed by coiling an electric wire aroundthe core of a doughnut shaped hollow disk. With regard to the electricwire, for example, it is preferable to use coiled ones located at fourpositions at every 90°. The magnet coil 216 may be arranged at theoutside of the blanking deflector 212, for example.

FIG. 8 is a flowchart showing main steps of a beam incident angleadjustment method according to the first embodiment. In FIG. 8, the beamincident angle adjustment method according to the first embodimentexecutes a series of steps: a defocusing setting step (S102), a beam-onsetting step (S104), a coil current setting step (S106), a lens valuetemporary setting step (S108), an irradiation position measuring step(S110), a positional deviation amount calculation step (S112), adetermination step (S114), and a lens value setting step (S120).Moreover, a writing method according to the first embodiment executes aseries of steps: each step of the beam incident angle adjustment methodand a writing step (S122).

First, a usual adjustment of the electron optical system is performed.In such a state, for example, when not performing beam deflection otherthan a blanking operation, the incident angle 9 (landing angle) of theelectron beam 200 to the surface of the target object 101 at theblanking voltage of during the beam-on period is unknown.

In the defocusing setting step (S102), first, the voltage applied to theobjective lens 207 is adjusted, and the focus position of the electronbeam 200 is intentionally displaced (defocused) from the surface of thetarget object 101 (the surface of the mark 106). Alternatively, thefocus position may be displaced using an electrostatic lens, etc. (notshown). Specifically, the writing control unit 66 outputs a controlsignal to the control circuit 120. The control circuit 120 applies avoltage to the objective lens 207 so that the lens value may be aspecified one.

The example described above is effective particularly when the heightposition of the mark 106 on the XY stage 105 is set to be the same asthat of the surface of the target object 101. However, it is not limitedto the case where the focus position is displaced by the objective lens207. For example, it is also preferable to preliminarily form the heightposition of the mark 106 on the XY stage 105 to be displaced by AZ fromthe height position of the surface of the target object 101.Alternatively, it is also preferable that a Z stage mechanism is addedto the XY stage 105 in order to displace the focus position of theelectron beam 200 from the surface of the target object 101 by movingthe XY stage 105 in the height-wise direction.

In the beam-on setting step (S104), a voltage for beam-on is applied tothe blanking deflector 212. Here, no voltage change or a change of anignorable extent occurs in the voltage at the beam-on time of theblanking deflector 212. Alternatively, a voltage change may occur.Specifically, the writing control unit 66 outputs a control signal tothe control circuit 120. The control circuit 120 outputs the controlsignal to the DAC amplifier 122 so that the deflection amount may be aspecified one. After converting the digital signal to an analog signal,the DAC amplifier 122 amplifies it to be applied as a deflection voltageto the blanking deflector 212. Since it is the voltage for beam-on inthis case, 0V voltage is applied, for example.

In the coil current setting step (S106), a current for a deflectionamount which is smaller than a deflection amount for deflection to makea beam-off state by the blanking deflector 212 is supplied to the magnetcoil 216. In other words, the electron beam 200 is deflected by theblanking aperture 214 in the extent of deflection not to trigger abeam-off state. It is preferable that this deflection amount is largerthan a deflection amount generated by a voltage change of during abeam-on period of the blanking deflector 212. This is because if settingto be described later is performed by the preferably larger deflectionamount (deflection voltage), the beam incident angle does not deviate bya voltage change amount less than the larger deflection amount.Specifically, the writing control unit 66 outputs a control signal tothe control circuit 120. The control circuit 120 outputs the controlsignal to the coil control circuit 134 so that the current value may bea specified one. The coil control circuit 134 supplies the specifiedcurrent to the magnet coil 216.

FIGS. 9A and 9B are conceptual diagrams for explaining a beam deflectionby a magnet coil according to the first embodiment. As described above,when performing a blanking deflection of the electron beam 200 by theblanking deflector 212, the deflection fulcrum is located in the centerheight position H of the blanking deflector 212. Then, as shown in FIG.9A, the magnet coil 216 is arranged in the center height position H ofthe blanking deflector 212. Thereby, as shown in FIG. 9B, the center ofthe magnetic field of the magnet coil 216 can be formed in the centerheight position H of the blanking deflector 212. A beam trajectorysimilar (symmetrical) to the one in the case of deflection by theblanking deflector 212 can be formed by deflecting an electron beam byusing the magnet coil 216.

FIG. 10 shows an example of a blanking trajectory and a beam trajectoryby a coil according to the first embodiment. FIG. 10 shows a result ofcalculation of simulating a beam trajectory for which blankingdeflection in the extent not to trigger a beam-off state has beenperformed by the blanking deflector 212. Furthermore, FIG. 10 also showsa result of calculation of simulating a beam trajectory when a beamdeflection is performed by the magnet coil 216 such that the deflectionamount is to be the same. As shown in FIG. 10, both the trajectories arealmost the same. Therefore, it turns out that it is effective to deflectthe electron beam 200 by using the magnet coil 216 instead of theblanking deflector 212 when measuring a beam incident angle.

FIG. 11 is a conceptual diagram for explaining an arrangement positionof a magnet coil according to the first embodiment. In the exampledescribed above, although the magnet coil 216 is arranged in the centerheight position H of the blanking deflector 212, it is not limited tothe case where the center of the magnet coil 216 is perfectly inaccordance with the center height position H of the blanking deflector212. The same effect can be produced in a case such as the case wheresome part of the magnet coils 216 is arranged in the center heightposition H of the blanking deflector 212 as shown in FIG. 11, forexample.

In the lens value temporary setting step (S108), a temporary appliedvoltage is set in the electron lens 211. It is acceptable to first usethe lens value, as it is, which was set in a usual adjustment of theelectron optical system. Specifically, the writing control unit 66outputs a control signal to the control circuit 120. The control circuit120 outputs the control signal to the lens control circuit 130 so thatthe voltage value may be a specified one. The lens control circuit 130applies the specified voltage to the electron lens 211.

In the irradiation position measuring step (S110), the measurement unit60 irradiates the electron beam 200 onto the target object 101 in thestate described above, and measures the irradiation position of theelectron beam 200 irradiating the target object 101. Specifically,first, the XY stage 105 is moved so that the mark 106 on the XY stage105 may be arranged at a designed irradiation position of the electronbeam 200. In such a state, scanning is performed in the x and ydirections on the mark 106, which is assumed to be the surface of thetarget object 101, by irradiating the electron beam 200 and deflectingit in the x and y directions by the sub deflector 209, for example.Then, the detection device 220 detects (measures) a reflected electronor a secondary electron generated at the mark 106 and its circumference.The output of the detection device 220 is converted into a digitalsignal and amplified by the amplifier 138, and input into the controlcomputer 110. In the control computer 110, the measurement unit 60calculates an irradiation position of the beam based on a scanningresult. The irradiation position of the beam is output outside throughthe external I/F circuit 112 and the like.

In the positional deviation amount calculation step (S112), thepositional deviation amount calculation unit 62 calculates a positionaldeviation amount from the design position of the irradiation position ofthe beam. The positional deviation amount is output outside through theexternal I/F circuit 112 and the like.

As described above, a positional deviation amount Δx from the designposition of a beam irradiation position is measured. Although, in thiscase, the positional deviation amount Δx in the x direction is describedin order to clarify the explanation, it is preferable to similarlymeasure also a positional deviation amount in the y direction.

In the determination step (S114), the determination unit 64 determineswhether a positional deviation amount is less than or equal to anallowable value L. Then, as a result of the determination, when thepositional deviation amount is not less than or equal to the allowablevalue L, it returns to the lens value temporary setting step (S108).When the positional deviation is less than or equal to the allowablevalue L, it goes to the lens value setting step (S120). In the lensvalue temporary setting step (S108), the lens value is set as a variableand steps from the lens value temporary setting step (S108) to thedetermination step (S114) are repeated until the positional deviationamount becomes less than or equal to the allowable value L.

As described above, a voltage for beam-on is applied to the blankingdeflector 212, an electron beam is converged by varying a voltageapplied to the electron lens 211 while supplying to the magnet coil 216a current for a deflection amount which is smaller than a deflectionamount for deflection to make a beam-off state by the blanking deflector212, and a positional deviation amount of the irradiation position ofthe electron beam 200 irradiating the target object 101 is measured foreach voltage applied to the electron lens 211. It is determined, foreach voltage applied to the electron lens, whether the positionaldeviation amount is less than or equal to the allowable value L. If thepositional deviation amount is less than or equal to the allowable valueL, the beam incident angle θ can be a perpendicular incidencesubstantially.

In the lens value setting step (S120), the lens value (voltage value) atthe time of a positional deviation amount becoming less than or equal tothe allowable value L is set to the electron lens 211. As describedabove, the voltage to be applied to the electron lens 211 is adjusted sothat the positional deviation amount of a beam irradiation position maybe within the allowable value L. Specifically, the writing control unit66 outputs a control signal to the control circuit 120. The controlcircuit 120 outputs the control signal to the lens control circuit 130so that the voltage value may be a specified one. The lens controlcircuit 130 applies the specified voltage to the electron lens 211.

Thus, the crossover position of the electron beam 200 converged by theelectron lens 211 is adjusted to be in the center height position H ofthe blanking deflector 212. Therefore, as explained with reference toFIGS. 3B and 5A, when the crossover position is set to be in the centerheight position of the blanking deflector 212, even if a blankingvoltage change occurs, the electron beam 200 enters the surface of thetarget object 101 at an angle substantially equivalent to aperpendicular incidence. In other words, it is possible to make the beamincident angle θ be approximately 0°.

As described above, according to the first embodiment, it is possible tomake a beam incident angle to the target object surface unchanged evenwhen a blanking voltage changes during a beam-on period.

In the writing step (S122), a pattern is written on the target object101 by using the electron beam 200 whose incident angle to the targetobject surface has been adjusted by the above-described method ofadjusting a beam incident angle to the surface of the target object 101,while a blanking operation is being performed by the blanking deflector212. The writing operation is what has been described above. Theposition accuracy of writing can be increased by performing writing bythe writing apparatus 100 whose incident angle has been adjusted asdescribed above.

Second Embodiment

Although, in the first embodiment, the magnet coil 216 is arranged inthe center height position H of the blanking deflector 212, theconfiguration for forming the same beam trajectory as that deflected bythe blanking deflector 212 is not limited thereto. In the secondembodiment, the same beam trajectory as that deflected by the blankingdeflector 212 is formed by using a plurality of magnet coils accordingto another configuration.

FIG. 12 is a conceptual diagram showing the configuration of a writingapparatus according to the second embodiment. FIG. 12 is the same asFIG. 1 except that, instead of the magnet coil 216, a plurality ofmagnet coils 218 and 219 are arranged at positions different from thatof the magnet coil 216. Moreover, the flowchart showing main steps of abeam incident angle adjustment method according to the second embodimentis the same as that of FIG. 8. The content of the second embodiment isthe same as that of the first embodiment except what is particularlydescribed below.

FIG. 13 is a conceptual diagram for explaining arrangement positions ofa plurality of magnet coils and a beam deflection by a plurality ofmagnet coils according to the second embodiment. In the secondembodiment, as shown in FIG. 13, a plurality of magnet coils 218 and 219are arranged backward of the blanking deflector 212 with respect to thedirection of the optical axis. The electron beam 200 is deflected by themagnet coils 218 and 219. The arrangement positions of a plurality ofmagnet coils 218 and 219 may be arbitrary positions as long as they arebackward of the blanking deflector 212 and forward of the finalcrossover position with respect to the direction of the optical axis.

In the coil current setting step (S106), a plurality of magnet coils 218and 219 receive a current for a deflection amount which is smaller thana deflection amount for deflection to make a beam-off state by theblanking deflector 212, wherein the intersection of the optical axis andan extended line of the trajectory of the electron beam 200 deflected bya plurality of magnet coils 218 and 219 is located in the center heightposition H of the blanking deflector 212. In other words, the electronbeam 200 is deflected by the blanking aperture 214 in the extent ofdeflection not to trigger a beam-off state. Thereby, the magnetic fieldformed by a plurality of magnet coils 218 and 219 is adjusted so thatthe intersection of the optical axis and the extended line of thetrajectory of the electron beam 200 deflected by a plurality of magnetcoils 218 and 219 may be located in the center height position of theblanking deflector 212. By virtue of employing a plurality of magnetcoils 218 and 219, the beam can be deflected from the optical axis bythe magnet coil 218 and a reverse deflection can be performed forreversing a part of a deflection amount of the deflection of the beam bythe magnet coil 219. By this multi-stage deflection, the intersection ofthe optical axis and the extended line of the trajectory of the electronbeam 200 is adjusted to be located in the center height position of theblanking deflector 212. When the magnet coil is not arranged in thecenter height position H of the blanking deflector 212, it is necessaryto perform reverse deflection for the deflected beam in order to adjusta beam trajectory such that the deflection fulcrum is apparently locatedin the center height position of the blanking deflector 212. This can beattained by a plurality of magnet coils 218 and 219. Specifically, thewriting control unit 66 outputs a control signal to the control circuit120. The control circuit 120 outputs the control signal to the coilcontrol circuit 134 so that it may be a combination of specified currentvalues. The coil control circuit 134 respectively supplies specifiedcurrents to the magnet coils 218 and 219. It is preferable that adeflection amount by the magnet coils 218 and 219 is a voltage largerthan that changes_during a beam-on period of the blanking deflector 212.

As described above, with the configuration according to the secondembodiment, the same effect as that of the first embodiment can beproduced.

Third Embodiment

Although, in the embodiments described above, a minute deflection isproduced by using the magnet coil 216 or the magnet coils 218 and 219,it is not limited thereto. In the third embodiment, there will bedescribed a configuration in which an amplifier for adjustment isadditionally prepared to perform deflection by the blanking deflector212.

FIG. 14 is a conceptual diagram showing the configuration of a writingapparatus according to the third embodiment. FIG. 14 is the same as FIG.1 except that a DAC amplifier 123 is arranged instead of the magnet coil216 and the coil control circuit 132. Moreover, the flowchart showingmain steps of a beam incident angle adjustment method according to thethird embodiment is the same as that of FIG. 8 except that coil currentsetting (blanking deflection adjustment) of S106 in FIG. 8 is read as“blanking deflection adjustment”. The content of the third embodiment isthe same as that of the first or second embodiment except what isparticularly described below.

In FIG. 14, the DAC amplifier 123 (the second amplifier) is connected inparallel with the DAC amplifier 122 (the first amplifier) to theblanking deflector 212. It is sufficient for the DAC amplifier 123 tooutput a voltage for deflecting the electron beam 200 in the extent ofdeflection not to trigger a beam-off state. Therefore, the responsespeed of the DAC amplifier 123 may be slower than that of the DACamplifier 122.

In the blanking deflection adjustment step (S106), the DAC amplifier 123applies, to the blanking deflector 212, a voltage for deflecting theelectron beam 200 in the extent of deflection not to trigger a beam-offstate from the beam-on state by the blanking deflector 212. It ispreferable that this deflection amount is larger than that generated bya voltage change of during a beam-on period of the blanking deflector212. This is because if setting to be described later is performed bythe preferably larger deflection amount (deflection voltage), the beamincident angle does not deviate by a voltage change amount less than thelarger deflection amount. Specifically, the writing control unit 66outputs a control signal to the control circuit 120. The control circuit120 outputs the control signal to the DAC amplifier 123 so that thevoltage value may be a specified one. The DAC amplifier 123 converts thedigital signal to an analog signal to be amplified and applies thespecified voltage as a deflection voltage to the blanking deflector 212.

As described above, the same effect as that according to the first orsecond embodiment can be produced even when an amplifier for adjustmentis additionally prepared in order to perform deflection by the blankingdeflector 212.

Fourth Embodiment

In the fourth embodiment, there will be explained a configuration inwhich adjustment of a beam incident angle is performed by adjusting thebeam center on the objective lens 207. The content of the fourthembodiment is the same as that of the first, second, or third embodimentexcept what is particularly described below.

FIG. 15 is a conceptual diagram showing the configuration of a writingapparatus according to the fourth embodiment. FIG. 15 is the same asFIG. 1 except that a measurement unit 70, a positional deviation amountcalculation unit 72, and determination units 74 and 76 are arranged,instead of the measurement unit 60, the positional deviation amountcalculation unit 62, and the determination unit 64, in the controlcomputer 110, and except that a magnet coil 218, a coil control circuit133, and a lens control circuit 131 are added. Each function such as themeasurement unit 70, the positional deviation amount calculation unit72, the determination units 74 and 76, and the writing control unit 66may be configured by hardware such as an electronic circuit or bysoftware such as a program causing a computer to implement thesefunctions. Alternatively, it may be configured by a combination ofhardware and software. Data which is input and output to/from themeasurement unit 70, the positional deviation amount calculation unit72, the determination units 74 and 76, and the writing control unit 66and data being calculated are stored in the memory 112 each time. Withregard to the lens control circuit 131, it should be understood thatdescription of it is omitted in the figure, although it exists, or it isincluded in the control circuit 120, in the first, second, and thirdembodiments. The magnet coil 218 is arranged between the blankingdeflector 212 and the objective lens 207. It is preferable for theheight position of the mark 106 to be the same as that of the surface ofthe target object 101. The height position of arrangement itself of themark 106 may be the same as that of the surface of the target object101, or the height position of the mark 106 may be adjusted to be thesame as that of the surface of the target object 101 at the time ofwriting by adding a Z-stage mechanism to the XY stage 105 in order tomove the XY stage 105 in the height direction.

FIG. 16 is a conceptual diagram showing another configuration of awriting apparatus according to the fourth embodiment. FIG. 16 is thesame as FIG. 15 except that the DAC amplifier 123 is arranged instead ofthe magnet coil 216 and the coil control circuit 132.

As shown in FIG. 4B, when the crossover position is set to be higherthan the center height position of the blanking deflector 212, if ablanking voltage change occurs, the beam center position of the electronbeam 200 deviates from the center of the magnetic field of the objectivelens 207. Then, using this phenomenon, according to the fourthembodiment, adjustment of a beam incident angle is performed byadjusting an applied voltage to the electron lens 211 so that the beamcenter position of the electron beam 200 may approach the center of themagnetic field of the objective lens 207.

FIG. 17 is a flowchart showing main steps of a beam incident angleadjustment method according to the fourth embodiment. In FIG. 17, thebeam incident angle adjustment method according to the fourth embodimentexecutes a series of steps: a lens value temporary setting step (S202),a beam-on setting step (S204), a beam center move step (S206), anobjective lens setting (1) step (S208), an irradiation positionmeasuring step (S210), an objective lens setting (2) step (S212), anirradiation position measuring step (S214), a determination step (S216),a blanking deflection adjustment step (S218), a beam center move step(S220), an objective lens setting (1) step (S222), an irradiationposition measuring step (S224), an objective lens setting (2) step(S226), an irradiation position measuring step (S228), a determinationstep (S230), a determination step (S232), and a lens value setting step(S234). Moreover, the writing method according to the fourth embodimentexecutes a series of steps: each step of the beam incident angleadjustment method and a writing step (S236).

In the lens value temporary setting step (S202), a temporary appliedvoltage is set in the electron lens 211. It is acceptable to first usethe lens value, as it is, which was set in a usual adjustment of theelectron optical system. Specifically, the writing control unit 66outputs a control signal to the control circuit 120. The control circuit120 outputs the control signal to the lens control circuit 130 so thatthe voltage value may be a specified one. The lens control circuit 130applies the specified voltage to the electron lens 211.

In the beam-on setting step (S204), a voltage for beam-on is applied tothe blanking deflector 212. Here, no voltage change or a change of anignorable extent occurs in the voltage at the beam-on time of theblanking deflector 212. Alternatively, a voltage change may occur.Specifically, the writing control unit 66 outputs a control signal tothe control circuit 120. The control circuit 120 outputs the controlsignal to the DAC amplifier 122 so that the deflection amount may be aspecified one. After converting the digital signal to an analog signal,the DAC amplifier 122 amplifies it to be applied as a deflection voltageto the blanking deflector 212. Since it is the voltage for beam-on inthis case, 0V voltage is applied, for example.

In the beam center move step (S206), the center of the electron beam 200is moved by deflecting the electron beam 200 toward the center of theobjective lens 207 by using the magnet coil 218. It is desirable toadjust so that the center position of the electron beam 200 may belocated at the center position of the magnetic field of the objectivelens 207. Specifically, the writing control unit 66 outputs a controlsignal to the control circuit 120. The control circuit 120 outputs thecontrol signal to the coil control circuit 133 so that the current valuemay be a specified one. The coil control circuit 133 supplies thespecified current to the magnet coil 218. Here, first, a temporarycurrent value is set.

In the objective lens setting (1) step (S208), the focus position of theelectron beam 200 is set by the objective lens 207. The focus is, inthis case, set at a height position different from that of the mark 106height. Specifically, the writing control unit 66 outputs a controlsignal to the control circuit 120. The control circuit 120 outputs thecontrol signal to the lens control circuit 131 so that the voltage valuemay be a specified one. The lens control circuit 131 applies thespecified voltage to the objective lens 207.

FIG. 18 shows an example of the focus position according to the fourthembodiment. In FIG. 18, the focus position is set to be upward ordownward of the height position of the mark 106 (the surface position ofthe target object 101). In this case, the focus position (focus 1) isadjusted to be upward (positive (+) in the z direction), for example.

In the irradiation position measuring step (S210), the measurement unit70 irradiates the electron beam 200 onto the mark 106 (target object101) in the state described above, and measures the irradiation positionof the electron beam 200 irradiating the mark 106 (target object 101).Specifically, first, the XY stage 105 is moved so that the mark 106 onthe XY stage 105 may be arranged at a designed irradiation position ofthe electron beam 200. In such a state, scanning is performed in the xand y directions on the mark 106 by irradiating the electron beam 200and deflecting it in the x and y directions by the sub deflector 209,for example. Then, the detection device 220 detects (measures) areflected electron or a secondary electron generated at the mark 106 andits circumference. The output of the detection device 220 is convertedinto a digital signal and amplified by the amplifier 138, and input intothe control computer 110. In the control computer 110, the measurementunit 70 calculates an irradiation position of the beam based on ascanning result. The irradiation position of the beam is output outsidethrough the external I/F circuit 112 and the like.

In the objective lens setting (2) step (S212), the focus position of theelectron beam 200 is set at another height position by the objectivelens 207. Here, also, the focus is set at a height position differentfrom that of the mark 106. In this case, as shown in FIG. 18, the focusposition (focus 2) is adjusted to be downward (negative (−) in the zdirection), for example.

In the irradiation position measuring step (S214), the measurement unit70 irradiates the electron beam 200 onto the mark 106 (target object101) in the state described above, and measures the irradiation positionof the electron beam 200 irradiating the mark 106 (target object 101).Specifically, scanning is performed in the x and y directions on themark 106 by irradiating the electron beam 200 and deflecting it in the xand y directions by the sub deflector 209, for example. Then, thedetection device 220 detects (measures) a reflected electron or asecondary electron generated at the mark 106 and its circumference. Theoutput of the detection device 220 is converted into a digital signaland amplified by the amplifier 138, and input into the control computer110. In the control computer 110, the measurement unit 70 calculates anirradiation position of the beam based on a scanning result. Theirradiation position of the beam is output outside through the externalI/F circuit 112 and the like.

In the determination step (S216), first, the positional deviation amountcalculation unit 72 calculates a difference between the irradiationposition on the mark 106 at the positive (+) side focus positionindicated by the focus 1 and the irradiation position on the mark 106 atthe negative (−) side focus position indicated by the focus 2. Then, thedetermination unit 74 determines whether the positional deviation amountbetween the measured irradiation positions is less than or equal to athreshold value Δ1 (first threshold value). If the positional deviationamount between the measured irradiation positions is not less than orequal to the threshold value Δ1, it returns to the beam center move step(S206), and repeats steps from the beam center move step (S206) to thedetermination step (S216) until the positional deviation amount becomesless than or equal to the threshold value Δ1. The closer the centerposition of the electron beam 200 approaches the center position of themagnetic field of the objective lens 207, the smaller the deviationamount between the measured irradiation positions becomes. That is, ifthe positional deviation amount between the measured irradiationpositions is less than or equal to the threshold value Δ1, it means thatthe center position of the electron beam 200 has further approached thecenter position of the magnetic field of the objective lens 207. Inother words, the center of the electron beam 200 is moved toward thecenter of the objective lens 207 by using the magnet coil 218 so thatthe positional deviation amount between the measured irradiationpositions may be less than or equal to the threshold value Δ1.

In the blanking deflection adjustment step (S218), in the case of FIG.15, a current for a deflection amount which is smaller than a deflectionamount for deflection to make a beam-off state by the blanking deflector212 is supplied to the magnet coil 216. In other words, the electronbeam 200 is deflected by the blanking aperture 214 in the extent ofdeflection not to trigger a beam-off state. It is preferable that thisdeflection amount is larger than that generated by a voltage change ofduring a beam-on period of the blanking deflector 212. This is becauseif setting to be described later is performed by the preferably largerdeflection amount (deflection voltage), the beam incident angle does notdeviate by a voltage change amount less than the larger deflectionamount. Specifically, the writing control unit 66 outputs a controlsignal to the control circuit 120. The control circuit 120 outputs thecontrol signal to the coil control circuit 134 so that the current valuemay be a specified one. The coil control circuit 134 supplies thespecified current to the magnet coil 216.

Alternatively, in the case of the example of FIG. 16, the DAC amplifier123 applies, to the blanking deflector 212, a voltage for deflecting theelectron beam 200 in the extent of deflection not to trigger a beam-offstate from the beam-on state by the blanking deflector 212. It ispreferable that this deflection amount is larger than that generated bya voltage change of during a beam-on period of the blanking deflector212. This is because if setting to be described later is performed bythe preferably larger deflection amount (deflection voltage), the beamincident angle does not deviate by a voltage change amount less than thelarger deflection voltage. Specifically, the writing control unit 66outputs a control signal to the control circuit 120. The control circuit120 outputs the control signal to the DAC amplifier 123 so that thevoltage value may be a specified one. The DAC amplifier 123 converts thedigital signal to an analog signal to be amplified and applies thespecified voltage as a deflection voltage to the blanking deflector 212.

In the beam center move step (S220), the center of the electron beam 200is moved by deflecting the electron beam 200 toward the center of theobjective lens 207 by using the magnet coil 218. It is desirable toadjust so that the center position of the electron beam 200 may belocated at the center position of the magnetic field of the objectivelens 207. Specifically, the writing control unit 66 outputs a controlsignal to the control circuit 120. The control circuit 120 outputs thecontrol signal to the coil control circuit 133 so that the current valuemay be a specified one. The coil control circuit 133 supplies thespecified current to the magnet coil 218. Here, first, a temporarycurrent value is set.

In the objective lens setting (1) step (S222), the focus position of theelectron beam 200 is set by the objective lens 207. The focus is, inthis case, set at a height position different from that of the mark 106height. As shown in FIG. 18, the focus position (focus 1) is adjusted tobe upward (positive (+) in the z direction) in this case.

In the irradiation position measuring step (S224), the measurement unit70 irradiates the electron beam 200 onto the mark 106 (target object101) in the state described above, and measures the irradiation positionof the electron beam 200 irradiating the mark 106 (target object 101).Specifically, first, the XY stage 105 is moved so that the mark 106 onthe XY stage 105 may be arranged at a designed irradiation position ofthe electron beam 200. In such a state, scanning is performed in the xand y directions on the mark 106 by irradiating the electron beam 200and deflecting it in the x and y directions by the sub deflector 209,for example. Then, the detection device 220 detects (measures) areflected electron or a secondary electron generated at the mark 106 andits circumference. The output of the detection device 220 is convertedinto a digital signal and amplified by the amplifier 138, and input intothe control computer 110. In the control computer 110, the measurementunit 70 calculates an irradiation position of the beam based on ascanning result. The irradiation position of the beam is output outsidethrough the external I/F circuit 112 and the like.

In the objective lens setting (2) step (S226), the focus position of theelectron beam 200 is set at another height position by the objectivelens 207. Here, also, the focus is set at a height position differentfrom that of the mark 106. In this case, as shown in FIG. 18, the focusposition (focus 2) is adjusted to be downward (negative (−) in the zdirection), for example.

In the irradiation position measuring step (S228), the measurement unit70 irradiates the electron beam 200 onto the mark 106 (target object101) in the state described above, and measures the irradiation positionof the electron beam 200 irradiating the mark 106 (target object 101).Specifically, scanning is performed in the x and y directions on themark 106 by irradiating the electron beam 200 and deflecting it in the xand y directions by the sub deflector 209, for example. Then, thedetection device 220 detects (measures) a reflected electron or asecondary electron generated at the mark 106 and its circumference. Theoutput of the detection device 220 is converted into a digital signaland amplified by the amplifier 138, and input into the control computer110. In the control computer 110, the measurement unit 70 calculates anirradiation position of the beam based on a scanning result. Theirradiation position of the beam is output outside through the externalI/F circuit 112 and the like.

In the determination step (S230), first, the positional deviation amountcalculation unit 72 calculates a difference between the irradiationposition on the mark 106 at the positive (+) side focus positionindicated by the focus 1 and the irradiation position on the mark 106 atthe negative (−) side focus position indicated by the focus 2. Then, thedetermination unit 74 determines whether the positional deviation amountbetween the measured irradiation positions is less than or equal to thethreshold value Δ1 (first threshold value). If the positional deviationamount between the measured irradiation positions is not less than orequal to the threshold value Δ1, it returns to the beam center move step(S220), and repeats steps from the beam center move step (S220) to thedetermination step (S230) until the positional deviation amount becomesless than or equal to the threshold value Δ1. The closer the centerposition of the electron beam 200 approaches the center position of themagnetic field of the objective lens 207, the smaller the deviationamount between the measured irradiation positions becomes. That is, ifthe positional deviation amount between the measured irradiationpositions is less than or equal to the threshold value Δ1, it means thatthe center position of the electron beam 200 has further approached thecenter position of the magnetic field of the objective lens 207. Inother words, the center of the electron beam 200 is moved toward thecenter of the objective lens 207 by using the magnet coil 218 so thatthe positional deviation amount between the measured irradiationpositions may be less than or equal to the threshold value Δ1.

In the determination step (S232), the determination unit 76 determineswhether a difference (L1−L2) is less than or equal to a threshold valueΔ2 (the second threshold value), where L1 is a movement amount of thecenter of the electron beam 200 in a beam-on state (the state after thebeam-on setting step (S204)) and L2 is a movement amount of the centerof the electron beam 200 in a further deflected state (the state afterthe blanking deflection adjustment step (S218)) changed from the beam-onstate.

It is also preferable to obtain a movement amount L1 of the beam centerin a beam-on state by converting an accumulated change amount of acurrent input to the magnet coil 218. In other words, what is used isthe sum of moved distances of the beam center in the beam center movestep (S206) that has been performed until a positional deviation amountbetween the measured irradiation positions becomes less than or equal tothe threshold value Δ1 in the determination step (S216).

Similarly, it is also preferable to obtain a movement amount L2 of thebeam center in a further deflected state changed from the beam-on stateby converting an accumulated change amount of a current input to themagnet coil 218. In other words, what is used is the sum of moveddistances of the beam center in the beam center move step (S220) thathas been performed until a positional deviation amount between themeasured irradiation positions becomes less than or equal to thethreshold value Δ1 in the determination step (S230).

In the case where a difference (L1−L2) between the movement amounts L1and L2 of the beam center is not less than or equal to the thresholdvalue Δ2, it returns to the lens value temporary setting step (S202) andsets a next applied voltage to the electron lens 211. Then, steps fromthe lens value temporary setting step (S202) to the determination step(S232) are repeated until the difference (L1−L2) between the movementamounts L1 and L2 of the beam center becomes less than or equal to thethreshold value Δ2. In other words, each step described above isrepeated while varying a voltage applied to the electron lens 211 untilthe difference (L1−L2) becomes less than or equal to the threshold valueΔ2.

If the crossover position is adjusted to be in the center heightposition of the blanking deflector 212 by the electron lens 211, sincethe deflection fulcrum and the crossover position are not displaced fromeach other as described above, the beam center does not deviate from thecenter of the objective lens 207 as shown in FIG. 4A even if a minutedeflection is produced.

In the lens value setting step (S234), the lens value (voltage value) atthe time of a difference (L1−L2) becoming less than or equal to thethreshold value Δ2 is set to the electron lens 211. As described above,the voltage to be applied to the electron lens 211 is adjusted so thatthe difference (L1−L2) may be less than or equal to the threshold valueΔ2. Specifically, the writing control unit 66 outputs a control signalto the control circuit 120. The control circuit 120 outputs the controlsignal to the lens control circuit 130 so that the voltage value may bea specified one. The lens control circuit 130 applies the specifiedvoltage to the electron lens 211.

Thus, the crossover position of the electron beam 200 converged by theelectron lens 211 is adjusted to be in the center height position H ofthe blanking deflector 212. Therefore, as explained with reference toFIGS. 3B and 5A, when the crossover position is set to be in the centerheight position of the blanking deflector 212, even if a blankingvoltage change occurs, the electron beam 200 enters the surface of thetarget object 101 at an angle substantially equivalent to aperpendicular incidence. In other words, it is possible to make the beamincident angle θ be approximately 0°.

As described above, according to the fourth embodiment, it is possibleto make a beam incident angle to the target object surface unchangedeven when a blanking voltage changes during a beam-on period.

In the writing step (S236), similarly to the writing step (S122), apattern is written on the target object 101 by using the electron beam200 whose incident angle to the target object surface has been adjustedby the above-described method of adjusting a beam incident angle to thesurface of the target object 101, while a blanking operation is beingperformed by the blanking deflector 212.

Embodiments have been explained referring to concrete examples asdescribed above. However, the present invention is not limited to thesespecific examples. For example, the determination step (S114) todetermine whether a positional deviation amount is less than or equal toan allowable value L according to the first or second embodiment may becarried out outside the apparatus, not in the writing apparatus 100. Forexample, determination may be carried out by the user and the like.Moreover, calculation of a positional deviation amount may also beperformed outside the apparatus, not in the writing apparatus 100. Forexample, the calculation may be carried out by the user and the like.

While the apparatus configuration, control method, and the like notdirectly necessary for explaining the present invention are notdescribed, some or all of them may be suitably selected and used whenneeded. For example, although description of the configuration of acontrol unit for controlling the writing apparatus 100 is omitted, itshould be understood that some or all of the configuration of thecontrol unit is to be selected and used appropriately when necessary.

In addition, any other charged particle beam writing apparatus, methodof adjusting a beam incident angle to the target object surface, andcharged particle beam writing method that include elements of thepresent invention and that can be appropriately modified by thoseskilled in the art are included within the scope of the presentinvention.

Additional advantages and modification will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. (canceled) 2: A charged particle beam writing apparatus comprising:an emission unit configured to emit a charged particle beam; an electronlens configured to converge the charged particle beam; a blankingdeflector, arranged backward of the electron lens with respect to adirection of an optical axis, configured to deflect the charged particlebeam in a case of performing a blanking control of switching betweenbeam-on and beam-off; a blanking aperture member, arranged backward ofthe blanking deflector with respect to the direction of the opticalaxis, configured to block the charged particle beam having beendeflected to be in a beam-off state; a first amplifier configured toapply a voltage for beam-on and a voltage for beam-off to the blankingdeflector, and a second amplifier, in addition to the first amplifier,connected in parallel with the first amplifier to the blankingdeflector, configured to apply, to the blanking deflector, a voltage fordeflecting the charged particle beam to be in an extent of deflectionnot to trigger a beam-off state from a beam-on state by the blankingdeflector. 3: A method of adjusting a beam incident angle to a targetobject surface comprising: setting a voltage to be applied to anelectron lens for converging a charged particle beam; applying, with afirst amplifier, a voltage for beam-on to a blanking deflectorconfigured to deflect the charged particle beam, to be in a beam-onstate; and applying, with a second amplifier, in addition to the firstamplifier, the second amplifier connected in parallel with the firstamplifier to the blanking deflector, to the blanking deflector, avoltage for deflecting the charged particle beam to be in an extent ofdeflection not to trigger a beam-off state from a beam-on state by theblanking deflector.